[CPMD-list] about oxygen Ultra-soft PP generated by USPP

[Axel Kohlmeyer]

On Thu, 5 Apr 2007, qfzhang wrote:

hi!

QZ> Hi,
QZ>     Sorry for too many questions. I want to use US-PP in PIMD calculations, so I

it would be nice, if you would also answer questions to you.
e.g. i am _very_ curious to learn, why you were setting MESH.

QZ>  think it's much faster than the NC-PP. Is there any problem to use US-PP for PI
QZ> MD?

i'm not so sure about that. CP dynamics with ultra-softs are always a 
little bit more sensitive. also the ultra-soft part of the calculation
is not as much optimized as the norm-conserving part. furthermore, in 
the case of PIMD, it would depend a lot on whether you will do BO-MD 
or CP-MD. CP-MD with PIMD requires _very_ careful calibration of the
thermostats, if you add ultra-soft pseudopotentials to that equation,
you can find yourself easily on the road to desaster. 


QZ>     And I also want to know the format of the US-PPs using in CPMD.Can you tell 
QZ> me something about that?

CPMD reads the .uspp files the vanderbilt code generates directly 
(with the flag BINARY and when they are generated on the same platform).
you can also use the format utility to convert the .uspp files to 
text format and read them with the FORMATTED keyword (on any platform).
ultrasofts in UPF format are _not_ supported (nor is there a converter).

cheers,
   axel.

QZ>     Best wishes
QZ>                                                     Qianfan Zhang
QZ>                                                      2007-04-05
QZ>    
QZ> Axel Kohlmeyer д:
QZ> 
QZ> > On Mon, 2 Apr 2007, qfzhang wrote:
QZ> > 
QZ> > QZ> Hi,
QZ> > QZ>   Thanks for the reply! the input file is attached here.I use MESH 
QZ> > QZ> and DUAL, and
QZ> > 
QZ> > why MESH???
QZ> > 
QZ> > QZ> calculate a charged system. Is there some other keyword that 
QZ> > QZ> should be specified?
QZ> > 
QZ> > QZ>  I have tried to add l=2 to generate O US-PP.But it shows that 
QZ> > QZ>  \\' no tuning point fot state nnlz = 320 on iteration 1\\' what\\'s
QZ> > QZ> wrong with it? The files were also attached here.
QZ> > 
QZ> > as i was alluding to in the previous mail. this state is not bound.
QZ> > please check the literature on generating pseudopotentials...
QZ> > 
QZ> > QZ>    Another question is can I use UPF US-PP? I see there are UPF
QZ> > QZ> US-PP on the web page of PWscf.How can I change them between the
QZ> > QZ> UPF\\'s and FORMATTED\\'s?
QZ> > 
QZ> > there is no conversion between UPF and native uspp.
QZ> > anyways, i would actually primarily suspect the Zr and Ba
QZ> > pseudopotentials. the parameter set shipped with the vdb
QZ> > code was seemingly tuned for an older version of the code
QZ> > which had a different fitting algorithm. with the current
QZ> > code you get (unphysical) negative densities for both of them,
QZ> > so i would suspect _them_ before i suspect the d-channel of 
QZ> > the oxygen having an impact.
QZ> > 
QZ> > cheers,
QZ> >    axel.
QZ> >    
QZ> >    Best wishes
QZ> >                                                      Qianfan Zhang  
QZ> > Axel Kohlmeyer ??:
QZ> > 
QZ> >> On Mon, 2 Apr 2007, qfzhang wrote:
QZ> >> 
QZ> >> QZ> Hi, dear all!
QZ> >> 
QZ> >> dear qianfan zhang.
QZ> >> 
QZ> >> QZ>   I want to use USPP to generate the US-PP for oxygen in the
QZ> >> QZ> calculation of oxi de. But the result is not good in the oxide(even
QZ> >> QZ> I use very large supercell). I want to add l=2 channel in the O
QZ> >> 
QZ> >> first of all, if you don\\\'t tell us, what you are trying to do and
QZ> >> what your input looks like, i would strongly suspect that you are
QZ> >> doing something wrong, since the oxygen ultrasofts generated by 
QZ> >> bernd meyer _do_ work well with a large number of systems, even
QZ> >> oxides. so please provide some input that _proves_ that the 
QZ> >> pseudopotential is at fault. thanks.
QZ> >> 
QZ> >> QZ> US-PP, because I find that the TM-PP I used bef ore includes the d
QZ> >> QZ> channel.  But I find it is impossible for me to generate such a
QZ> >> 
QZ> >> you should be _very_ careful with that. pseudopotentials created
QZ> >> with the \\\'haman\\\' style PP code that are in the cpmd pp library
QZ> >> mostly contain a unbound, bogus d channel, which will either have
QZ> >> little contribution (if used with LMAX=D LOC=P) or may give worse
QZ> >> results (if used with LMAX=D, which implies LOC=D).
QZ> >> 
QZ> >> QZ> US-PP.Is there anyone who know how to do that?
QZ> >> 
QZ> >> adding another projector to existing USPP inputs is actually
QZ> >> rather straightforward. just follow the instructions in the 
QZ> >> INPUT_XX files that ship with the code. the problem is to have 
QZ> >> it converged and bound. so you may have to slightly oxidize
QZ> >> the atom and/or shift some fractional occupation to the d-state.
QZ> >> 
QZ> >> QZ>   Or who know some tricks to improve the quality of US-PP?
QZ> >> 
QZ> >> before you put too much effort into optimizating the potential,
QZ> >> you may be better off to stick with a reasonable norm-conserving
QZ> >> pseudopotential. you avoid some of the overhead and \\\'only\\\' need
QZ> >> some more cpus resources to distribute the work. but then again
QZ> >> with ultra-softs, CPMD usually does not scale that far, so in case
QZ> >> you have a large enough resource to run on, you may find NC-PPs 
QZ> >> about as efficient as US-PPs.
QZ> >> 
QZ> >> cheers,
QZ> >>    axel.
QZ> >> 
QZ> >> 
QZ> >>  
QZ> >>    Best wishes
QZ> >>                                                       Qianfan Zhang
QZ> >>                                                       2007-04-02
QZ> >> 
QZ> >> 
QZ> >> 
QZ> >> -- 
QZ> >> =======================================================================
QZ> >> Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
QZ> >>    Center for Molecular Modeling   --   University of Pennsylvania
QZ> >> Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
QZ> >> tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
QZ> >> =======================================================================
QZ> >> If you make something idiot-proof, the universe creates a better idiot.
QZ> >> 
QZ> > 
QZ> > 
QZ> > 
QZ> > 
QZ> > -- 
QZ> > =======================================================================
QZ> > Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
QZ> >    Center for Molecular Modeling   --   University of Pennsylvania
QZ> > Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
QZ> > tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
QZ> > =======================================================================
QZ> > If you make something idiot-proof, the universe creates a better idiot.
QZ> > 
QZ> 
QZ> 
QZ> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.